Fix flaky resolveNetworkAddress test

[ravicious]

I had the resolveNetworkAddress test fail randomly. resolveNetworkAddress failed with the following error:

Could not resolve address (unix:///tmp/test) for process /opt/hostedtoolcache/node/16.20.0/x64/bin/node: the process exited.

There are two problems here.

Truthiness check

The function which returns this error is called on the exit handler of a child process:

teleport/web/packages/teleterm/src/mainProcess/resolveNetworkAddress.ts

Lines 100 to 115 in 98d3eee

	const rejectOnExit = (code: number, signal: NodeJS.Signals) => {
	const codeOrSignal = [
	code && `code ${code}`,
	signal && `signal ${signal}`,
	]
	.filter(Boolean)
	.join(' and ');
	const details = codeOrSignal ? ` with ${codeOrSignal}` : '';
	rejectOnError(
	new ResolveError(
	requestedAddress,
	process,
	`the process exited${details}`
	)
	);
	};

Node.js docs say that either the code or the signal will be non-null, so why is neither of them present in the error message? Well, that's because code is a number and if it's 0, meaning the process exited without errors, then it's going to evaluate to false.

Race condition

The second problem: how did the child process exit without errors yet the test failed? The test spawns a child process running testProcess.js and then waits for the process to write {CONNECT_GRPC_PORT: 1337} to its stdout.

If the child process exit handler was triggered before the stdout data handler, then it must mean that testProcess.js exited before writing that message to stdout.

This is how testProcess.js looks like:

teleport/web/packages/teleterm/src/mainProcess/testProcess.js

Lines 1 to 19 in 98d3eee

	const process = require('process');
	const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
	(async () => {
	const waitTime = parseInt(process.argv[2]);
	if (waitTime) {
	await sleep(waitTime);
	}
	const shouldExit = process.argv[3];
	if (shouldExit) {
	process.exit(1);
	}
	console.log('Lorem ipsum dolor sit amet');
	console.log('{CONNECT_GRPC_PORT: 1337}');
	console.log('Lorem ipsum dolor sit amet');
	})();

I realized that there's nothing awaiting this anonymous async function, so it's totally possible for the process to just not write anything to stdout. Since top-level await is available in .mjs modules since Node v14, I rewrote the file to use it. This guarantees that the process will write to stdout before exiting.

[gzdunek]

Converting testProcess.js to ES modules is cool!

[gzdunek]

Can we be more strict? (code !== null)

[ravicious]

This is one of the cases where it covers both null and undefined. I want to perform a truthiness check on a number without treating 0 as falsy.

[public-teleport-github-review-bot]

@ravicious See the table below for backport results.

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branch/v13	Create PR